Water doesn't spoil.

The expiration dates on bottled water is artifical. It's not based on anything other than to get people to buy more water.
If you killed the bacteria and store the treated water properly, then it should be fine to drink YEARS after you stored it. No bacteria means there is nothing to multiply itself in the water, during storage. Proper storage containers will not leach anything harmful into the water. As pointed out above you may get a plastic flat taste if stored for a long time, but you can always pour the water back and forth between CLEAN containers to reoxyginate it.
That being said, I try to rotate my small supply every year.

By rotate, I mean USE the water, not just dump it. Water may seem to be unlimted, but in many places FRESH water isn't.